Thermal printer

Abstract

A thermal printer includes an inked ribbon, an inked ribbon take-up mechanism, a print head with two arrays of thermal resistance elements, a carriage mounting the print head, and a controller for controlling the print operation. The printer is provided with print mode switching circuit which selects low-speed print mode in which one array of thermal resistance elements is activated for each dot pitch for printing, or high-speed print mode in which the two arrays of thermal resistance elements are activated alternately for every dot pitch for printing. The printer having the print head with two thermal resistance elements is capable of high-speed printing and also high quality printing at a low print speed.

We claim: 
     
       1. A thermal printer comprising: a print head with a plurality of arrays of in-line thermal elements,   a carriage mounting said print head,   a controller for controlling the printing operation, and   print mode switching means which selects low-speed print mode in which one array of thermal elements is activated for each dot pitch for printing, or high-speed print mode in which the arrays are activated cyclically for every dot pitch for printing.   
     
     
       2. A thermal printer comprising: a print head with two arrays of in-line thermal elements,   a carriage mounting said print head,   a controller for controlling the printing operation, and   print mode selection means which selects low-speed print mode in which one array of thermal elements is activated for each dot pitch for printing, or high-speed print mode in which the two arrays of thermal elements are activated alternately for every dot pitch for printing.   
     
     
       3. A thermal printer comprising: an inked ribbon,   an inked ribbon take-up mechanism,   a print head with two arrays of in-line thermal elements,   a carriage mounting said print head,   a controller for controlling the printing operation, and   print mode switching means which selects low-speed print mode in which one array of thermal elements is activated for each dot pitch for printing, or high-speed print mode in which the two arrays of thermal elements are activated alternately for every dot pitch for printing.   
     
     
       4. A thermal printer comprising: a print head with two arrays of in-line thermal elements,   a carriage mounting said print head,   an inked ribbon case mounted on said carriage,   a supply reel and take-up reel mounted on said inked ribbon case,   an inked ribbon wound on said supply and take-up reels,   a reel driver for spinning said supply reel,   a carriage driver for moving said carriage, and   print mode switching means which selects low-speed print mode in which one array of thermal elements is activated for each dot pitch for printing, or high-speed print mode in which the arrays of thermal elements are activated alternately for every dot pitch for printing.   
     
     
       5. A thermal printer according to claim 4, wherein said print mode switching means changes said arrays of the in-line thermal element to be activated for every print line or every predetermined number of print lines during the low-speed print mode.